The present invention relates to a well casing hanger and, more particularly, to an adjustable casing hanger for adjustably suspending a tieback casing string which is connected to a subsea wellhead from a surface wellhead located on a offshore drilling or completion rig.
A tieback casing string is generally required in offshore petroleum production installations to provide a fluid conduit between a subsea wellhead and a surface wellhead located on an offshore drilling or completion rig. An adjustable casing hanger is typically used to space out the tieback casing string between these two components. Heretofore, adjustable mandrel-type casing hangers have been used for this purpose. Prior art mandrel-type casing hangers generally comprise a first tubular member which is connected to the tieback casing string and a second tubular member which includes a support surface for engaging a support shoulder formed in the surface wellhead. The first and second tubular members are movably connected to vary the distance between the tieback casing string and the surface wellhead.